allen



UNITED STATES PATENT OFFICE.

JNO. F. ALLEN, OF NEW YORK, N. Y.

VALVE-GEARING FOR STEAM-ENGINES.

Speccaton of Letters Patent No. 20,768, dated June 29, 1858.

To all whom it may concern:

Be it known that I, Jol-IN F. ALLEN, of the city, county, and State ofNew York, have invented a new and Improved Valve- Gear forSteam-Engines; and I do hereby declare that the following is a full,clear, and exact description of the same, reference being had to theaccompanying drawings, making part of this specification, in which-Figure l is a side view of the steam chest of a horizontal engine withmy improved valve gear, the steam chest being represented with part ofits exterior broken away to expose to view the valves belonging to oneend of the cylinder'. Fig. 2 is a transverse vertical section 0f thevalve gear. Fig. 3 is a side View of part of the valve gear which isconcealed in Fig. 1.

Similar letters of reference indicate corresponding parts in the severalfigures.

This invention consists in a certain arrangement of parts for operatingthe Valve rockshaft of a steam engine in such a manner as to effect theinduction of the steam at the proper time and cut it oft at variouspoints in the stroke.

The invention, though represented in the drawing applied to slidevalves, can be used with puppet valves.

A, is the steam chest.

I, I', are the induction valves, consisting of slide valves of thesimplest kind, viz. mere plates, faced to fit and work upon their seata, a, to cover and uncover the induction ports 2', z".

E, E', are the eduction valves consisting like the induction valves ofsliding plates, and being fitted to a seat b, b, which is under the seata, a. In this seat b, o, are two sets of ports communicating with thecylinder viz. the eduction ports e, e, communicating with the eductionpipe, and two ports c, c, which coincide with the induction ports z',i', and serve as a communication in turn between the induction ports andthe cylinder and between the cylinder and the eduction ports. The valveseat b, b, while its ports c, e', and 0, c, are like the valve seat andports of steam engines now in use employ two short slide valves forinduction and eduction of steam; the ports e, c', corresponding withordinary eduction ports and c, 0, with ordinary induction ports. Theseat a, a, is placed on the face of that Z), o, either in two shortpieces of sufficient lengths for applied to an old engine constructedfor the use of two short slide valves of the ordinary kind. The eductionvalves E, E, are both attached to the same rod cl, which is intended tobe worked by an eccentric or other contrivance independent oftheinduction valve gear.

B is a rockshaft by which the induction valves are operated, the saidshaft passing through a stuiiing box in one side of the steam chest andat the middle of its length, and extending across the chest to asuitable bearing in the opposite side thereof. This shaft carries-withinthe steam chest A- two cams C, C', one for operating each valve; thesaid cams being surrounded by yokes D, D, which are connected by rods f,f, with the induction Valves. These cams are what are known astriangular cams, and are arranged at right angles to each other, so thatwhen one is opening or closing its respective valve, the other merelygives a vibrating motion to its respective rod, and thus makes thevalves independent of each other. This arrangement is illustrated inFig. 3, which represents the rockshaft, the cams, cam-yokes, rods andvalves. The rock shaft B is furnished outside the steam chest with armL, which is fitted with a sliding toe g, running right through it, andthis toe is connected with a rod j, by a pin a, which passes through a.slot h, in the outer face of the arm. The rod y', is fitted to slidethrough stationary guides le, 7c, and by sliding it down or up, thesliding toe g, is caused to project more or less beyond the extremity ofthe arm. The said rod may be adjusted by hand and secured by a set screwto effect a permanent adjustment of the sliding toe, or connected with agovernor to vary the adjustment according to the requirements of theengine, as will be presently described.

g, is an arm attached to the rockshaft B, and occupying a positionparallel to the arm L, and having attached to it a cord or chain t,which passes down between two pulleys u, u, and is connected with aspring o, which acts upon the cord with a tendency to draw the arms q,and L, to a position perpendicular to the valve seat. The pulleys u, u,are placed on fixed axles secured to the frame G.

F is an annular plate or open arm, encircling the arm L, and hung toswing upon a stud 1n, which is secured in a fixed frame G, attached tothe side of the steam chest; the axis of the said stud being parallelwith the rockshaft B, and in the same plane, perpendicular to the valveseat, as the axis of the rockshaft. At the opposite point in the saidplate or arm F, to where it is hung upon the ,stud 111/, the said plateor arm has attached to it by a pin p, a small swinging piece H, whichhas itsv upper end formed with two corners or points 1, 1, and which isattached at its lower end by a pin s, to the rod J, which is connectedwith the contrivance through which the motion of the valves is to bederived from4 the main shaft of the engine. An eccentric may be used forthis purpose. The distance which the piece H is permitted to swing` islimited by the form of the slot which is made in it to receive the armF.

The operation of the valve gear to open and close the valves I, I, forthe induction and cutting-off of the steam is as follows: The rod J,gives a swinging movement to the open arm F; but as the rod moves ineither direction, it moves the piece H, on the pin p, before commencingto move the said plate or arm, moving the said piece H to the positionrelatively to the said plate or arm shown in black outline in Fig. l, asit commences to move to the left, and to the other position as itcommences to move to the right. During the first part of the swingingmovement of the open arm F, the arm L, the rockshaft B, and the valvesI, I are stationary; and the arm L, is kept by the spring 1J, in aposition perpendicular to the valve seat in which lposition theinduction valves are both closed. As the upper point 1, or 11, of thepiece H, comes in contact with the toe g,-which always occurs at thecommencement of the stroke of the piston or just before that if thevalves have any lead as they always should have,-the arm L, is caused tomove with the plate or arm F, till the said point by reason of theradius of the open arm F, being greater than that of the arm L, worksclear of the toe g, and allows the arm L to be drawn back to theperpendicular position before mentioned, by the spring 1;, thus closingthe valve, and cutting olf the steam with what is known as a trippingmotion. It is obvious that the farther the toe g, is projected beyondthe extremity of the arm L, the greater distance will the said arm L bemoved before the toe escapes and the valve trips and vice versa; andhence by adjusting the rod 1', to project the toe less or more, thesteam may be cut ofl" earlier or later in the stroke of the engine, andthe cutting-off may be made to govern the engine by connecting the rod.7', with a"gov ernor. Fig. 1 represents in black outline the rod J, andarm F, moving in the direction of the black arrow and the point 1, ofthe piece H, in operation on the toe g; the movement not having beencontinued far enough for the toe to escape. In the same Fig. l, the armL is shown in red outline as having moved to the perpendicular positionafter the escape of the toe g, and the arm L returning to operate on thetoe g, with the point 1, uppermost or in the opposite ycondition to thatshown in black outline. The rocking piece H, is for the purpose ofproviding for giving a lead to the valve and it can be constructed oradjusted so that each of the points 1', 1, shall come into Contact withthe toe g, at the proper time to give the required lead. Vhen theinduction valves are worked independently of the eduction valves, asdescribed, the eccentric for working them may be set almost coincidentwith the cranks or only suiiiciently in advance to give a lead to thevalve, and then the cutting off of the steam may be caused to take placeat any point nearly up to the end of the stroke.

Vith this valve gear, the education valves may be operated by the sameeccentric as t-he induction valves. This operation may be effected bysubstituting for the stud m, a rockshaft with a connection therefrom tothe exhaust valves and securing the arm F to the said rockshaft, andeither driving the whole by the rod J, applied as described or by a rodotherwise applied to move the rockshaft m; but it is obvious that towork the eduction valves by the same eccentric, the eccentric must beset at right angles to the piston or thereabouts. This arrangement ofthe eccentric it may seem at first would compel the cutting off of thesteam within half stroke or else the working under a full head of steam.This however is not necessarily the case, if the motion is given by therod J, as the friction of the exhaust valves will be suflicient to holdthe open arm F, stationary during the iirst part of the return of therod J, which commences at half stroke; and the toe g, may be adjusted sothat it will not escape from the piece H, till said piece has beenturned partly over by t-he action of the rod; and as the movement of theeccentric rod is at that time very slow (the eccentric having but justpassed its center), and the movement of the piston is very rapid (beingjust past half stroke) as much as two-thirds of the stroke of the pistonmay be completed before the toe g, escapes and allows the valve to tripand cut off.

This is perhaps the first valve motion which permits of the tripping ofthe valves to cut off beyond half stroke, when a single eccentric isused, to Work the induction and eduction valves.

To apply the invention to puppet valves, all the same parts may be used,with the exception that different connections are required from thecam-yokes to the valves. The motion of the cams C, C, Will prevent theslamming of puppet valves Without using dash-pots.

I do not claim the use of a sliding toe like g, applied to the arm ofthe valve rockshaft but Having` thus described my invention, What Iclaim as new and desire to secure by Letters Patent, is

Tlie arrangement of the swinging plate or open arm F, with its twopointed swinging piece H, or equivalent, substantially as described, incombination With the single rockshaft B, its arm L, and movable toe g,to operate the tWo induction valves as described.

JOHN F. ALLEN. Witnesses:

W. TUSOH, W. HAUFF.

